1. Field of the Invention
The present invention is concerned generally with the conversion of labile primary and secondary unsaturated alcohols to their corresponding aldehydes and/or carboxylic acids and ketones respectively and more particularly with the production of chrysanthemic acid from the corresponding alcohol.
2. Description of the Prior Art
There are few general and inexpensive methods known for oxidation of labile primary alcohols selectively to aldehydes and/or acids. Lee, D. G. et al, in Can. J. Chem. vol 50, pages 3741 et seq. (1972) describe the use of sodium ruthenate (Na.sub.2 RuO.sub.4) as a reagent for oxidation of primary or secondary alcohols to the carboxy acids or ketone respectively. This process is not attractive for large scale operation in that a two step procedure is generally necessary for production of the acid and furthermore involves the use of highly expensive sodium ruthenate in stoichiometric quantity as oxidizing agent. This reagent cannot be efficiently employed as oxidizing agent for the oxidation of alcohols containing functional components that are sensitive to strong oxidizing agents, nor for oxidation of unsaturated alcohols which require elevated temperature and/or extended reaction time, since under these conditions the ruthenate attacks the carbon-carbon double bond with loss of yield of the desired unsaturated acid.
It has also been recently disclosed that in aqueous acetone, the primary alcohol function of sugars can be oxidized to the acid in low yield by an in situ combination of ruthenium tetroxide (RuO.sub.4) in catalytic amount with sodium periodate (NaIO.sub.4); Smejkae, J. et al, Coll. Czech. Chem. Comm., 38, 1981 (1973). It is known, on the other hand, however, that RuO.sub.4 attacks alkenes to form glycols which in turn are cleaved by NaIO.sub.4, so that the utility of this reagent for application to oxidation of unsaturated alcohols appears to be limited (Fatiadi, A. I., Synthesis, #4, 229 (1974)).
For the oxidation of chrysanthemyl alcohol to the corresponding carboxylic acid, it has hitherto been proposed to employ chromium trioxide in pyridine. (Published German Application OLS No. 2,164,024) see also Mills, R. W. et al, Jour. Chem. Soc. (Perkin I), 133 (1973). This process requires relatively long reaction periods for ultimate conversion of the intermediate aldehyde formed to the desired carboxy acid, which is obtained in only moderate yield.